1. Field of the Invention
The present invention generally relates to a digital video broadcasting (DVB) system. More particularly, the present invention relates to an apparatus and method for receiving data transmitted by employing bit interleaving, symbol interleaving and symbol mapping.
2. Description of the Related Art
A digital video broadcasting-handheld (DVB-H) system is a standard in which a 4K-mode fast Fourier transform (FFT) size, a multi-protocol encapsulation-forwarding error coding (MPE-FEC) function, a time-slicing function, a transmission parameter signaling (TPS) function, and the like are added to a DVB-terrestrial (DVB-T) system based on a European fixed digital television (DTV) standard in order to improve reception performance by considering a handheld service of a mobile channel's situation.
The DVB-H system transmits an audio/video (A/V) stream of a broadcast signal on the basis of an Internet protocol (IP). The DVB-H system can be exploited along with the DVB-T system using hierarchical modulation.
It is obvious that a data reception is a reverse operation to a data transmission. Thus, for reverse operations to bit interleaving, symbol interleaving and symbol mapping in a transmission stage of the DVB-H system, a reception stage sequentially performs symbol demapping, symbol deinterleaving and bit deinterleaving. However, when the symbol demapping is first performed before the symbol deinterleaving, a problem exists in that a memory size required for a symbol deinterleaver to use high order modulation such as 16/64-ary quadrature amplitude modulation (16/64-QAM) for the symbol mapping increases in proportion to the number of bits of a symbol-demapped soft value.
For example, the DVB system for supporting an FFT size in 8K mode will be described. When each soft value for configuring a demapped soft symbol from in-phase/quadrature phase (I/Q) data for subcarriers of an FFT unit is 7 bits and the modulation scheme is 64-QAM, the total number of memory bits required for the symbol deinterleaver is 6,048*6*7*2=508,032 bits. Herein, a value of 6,048 is the number of data subcarriers used in the 8K mode, a value of 6 is the number of soft values configuring the demapped soft symbol in the case of 64-QAM, a value of 7 is the number of bits of each soft value, and a value of 2 is the number of memories with the same size required for receiving the next input when a deinterleaved output is transmitted. A problem exists in that hardware complexity and power consumption are increased because the DVB system requires a large symbol deinterleaver memory of about 496K bits to support the 8K mode.
Accordingly, there is a need for an improved apparatus and method for receiving data in a wireless communication system that avoids an increase in hardware complexity and power consumption.